Gut Microbiota Modulators as Antibiotic Alternatives in Broiler Nutrition: A Review

Antibiotics have been widely used in broiler diets to improve growth performance and prevent enteric diseases; however, restrictions on their use have increased interest in alternative nutritional strategies. Among these, modulation of gut microbiota has emerged as a promising approach for replacing antibiotic growth promoters. The gut microbiota plays an essential role in nutrient digestion and absorption, immune development, pathogen resistance, and maintenance of intestinal barrier function in broilers. A balanced microbial community is closely associated with improved feed efficiency and growth performance, whereas microbial imbalance can impair intestinal function and increase disease susceptibility. Consequently, dietary interventions targeting gut microbial composition and activity have been extensively studied. This review summarizes recent research on gut microbiota modulators used as antibiotic alternatives in broiler diets, including probiotics, prebiotics, synbiotics, stimbiotics, postbiotics, and parabiotics. These additives generally increase beneficial bacteria such as <i>Lactobacillus</i> and <i>Bifidobacterium</i> while suppressing potential pathogens including <i>Escherichia coli</i> and <i>Clostridium perfringens</i>, thereby improving the intestinal environment and gut health. Although gut microbiota modulators show strong potential as antibiotic alternatives, further studies are required to clarify optimal application strategies and functional links between microbial changes and productive performance.